What does the term Black Friday refer to and where did it come from?

According to Kathy Grannis, director of media relations for the National Retail Federation, the origins of the term are disputed. But Grannis said that retailers typically attribute the term to the day after Thanksgiving when they see their sales go from “red (deficits)” into the “black (profits).” Other news sources, however, have traced the origins back to Philadelphia in the 1960s when police used the term to describe traffic jams and increased criminal activity on the day after Thanksgiving